Interobserver agreement for EUS in the evaluation and diagnosis of submucosal masses

introduction: EUS is an accurate means of evaluating and diagnosing submuco sal lesions of the GI tract. The aim of this study was to prospectively det ermine interobserver agreement for the EUS classification of submucosal mas ses among endosonographers with different levels of training and experience from multiple centers. Methods: Twenty patients with submucosal mass lesions diagnosed by upper en doscopy underwent EUS. Surgical findings were available for 16 patients. In 4 patients with obvious cystic/vascular structures (i.e., varices) no surg ical specimen was necessary. A blinded observer developed a study videotape of critical endoscopic and EUS real-time imaging for each lesion. The vide otape was distributed to 10 endosonographers, each with at least 1 year of experience, who independently reviewed the videotape and recorded their dia gnosis based on EUS features. These endosonographers used previously agreed -upon standardized EUS diagnostic criteria for each category of lesion. A k appa (kappa) statistic, used to evaluate agreement, was calculated for each lesion category for the 10 endosonographers as a group and individually. A n overall kappa statistic was also calculated. Significance was analyzed wi th a two-tailed t test. Results: Agreement was excellent for cystic lesions (kappa = 0.80) and extr insic compressions (Ic = 0.94), good for lipoma (kappa = 0.65), fair for le iomyoma end vascular lesions (kappa = 0.53 and 0.54, respectively), and poo r for other submucosal lesions (kappa = 0.34). Overall agreement among obse rvers was good (kappa = 0.63). Furthermore, a significant association was n oted between total years of EUS experience and the number of correct answer s (p = 0.01). Conclusions: Interobserver agreement is good for characterizing submucosal masses by EUS. However, it appears to be better for some lesions than other s. The overall length of experience with EUS appears to play an important r ole in the accuracy of this modality in the evaluation of submucosal lesion s.